1. Field of the Invention
This invention generally relates to acoustical instrumentation, specifically to the visual display of the acoustic properties of a space such as a room.
2. Description of the Related Art
A desire to provide optimal listening experiences in entertainment and education venues can motivate development of systems and methods for evaluating and/or adjusting acoustical behavior at one or more specified positions within a space, responsive to one or more specified excitation sources.
A commercial movie theater is just one example of a space in which acoustic response can be of particular interest. During the showing of a movie, the audience can comprise many persons, with each person disposed at his or her own specific position within the space. There are typically one or more loudspeakers in a commercial movie theater. The acoustical responses at specific positions in response to one or more of the loudspeakers can be characterized. That is, a response characteristic can be associated with a specific position, such as the position a member of the audience might have when seated in a particular chair. Such response characteristics can be usefully employed for analysis and adjustment of acoustical and electro-acoustical attributes of the space. In a typical movie theater environment, there can be a need to provide response characteristics at one or more positions that meet specified performance criteria. Adjustments to the response characteristics can be accomplished by one or more of many available techniques. These techniques can include, but are not limited to: making adjustments to the architectural acoustic properties of the space; signal processing applied to sound signals that are subsequently reproduced by one or more loudspeakers in a sound reinforcement system; adjusting the number, locations, directivity, and/or other properties of loudspeakers; and/or simply making arrangements to avoid having audience members disposed in specific positions that have relatively unfavorable response characteristics. In some cases, simply repositioning or removing a single chair can be a favorable adjustment.
Concert halls, home theaters, classrooms, auditoriums, and houses of worship are further examples of spaces where acoustic response can be of interest. It can be appreciated that the excitation source and/or sources need not be loudspeakers. For example, in a concert hall there can be a need to characterize the acoustical response at a particular audience position in response to a musical instrument such as a violin, as the violin is played at a specified position on a stage.
One established method of evaluating and adjusting the electro-acoustical behavior of exemplary spaces including auditoriums and listening or home theatre rooms is typically both complex and time-consuming. It involves manually setting up a single microphone or microphones arranged in an array within the listening room or auditorium. One set of data can be gathered from the initial set-up, but the microphones must be physically picked up from their initial positions, and put down in new positions around the room. This repositioning of the microphones is needed in order for the testing and adjusting to provide results having sufficiently useful coverage.
An excitation source can generate multiple frequency sweeps and/or impulses. Corresponding measurements from the microphones must be gathered and correlated with the microphone positions. Many iterations of testing steps and adjustments can be required in order to generate confident results. These iterations can include repositioning, adding, and/or removing: loudspeakers and/or furniture and/or wall treatments and/or floor treatments and/or ceiling treatments and/or bass traps and/or diffusers and/or sound absorption materials and/or other acoustic treatments. For each adjustment made, there can be a need to acquire another set of characterizing data. This data can be compared with previously gathered data in order to determine an extent to which acoustical performance goals are being met. This repeated data acquisition and analysis interspersed with small or large adjustments can require significant amounts of labor and/or materials, and can result in unfavorable time frames and/or expenses.
In some circumstances, an array of wired microphones can be employed. This can help to accelerate a testing and/or characterization process, as it allows for simultaneous measurements at multiple positions. However, an array of wired microphones and a measurement system capable of adequately receiving signals from those microphones can be costly and/or unwieldy. It is likely that for a given space, the array of microphones will need to be positioned multiple times, and used to acquire measurements multiple times, as adjustments are made and/or in order to adequately characterize acoustical response at positions of interest in the space.
Other extant methods of evaluating and/or adjusting acoustic and/or electro-acoustic behavior of specific spaces employ computational analysis; these methods can include computer-aided modal analysis and/or modeling. Even a relatively simply-defined space tends to have enormously complicated acoustical properties that can be important contributors to a characterized response. Due to this attendant complexity, computational analysis can be a fairly crude method of predicting acoustical behavior in exemplary spaces, and is generally most useful only when the geometry of the space considered is very simple. Assumptions made in order to simplify the analysis can effectively invalidate the results. Analysis is further complicated when multiple excitation sources (loudspeakers) and/or listening positions are taken into account.
Thus there is a need for a system and method to effectively characterize acoustic responses for positions within a space.